1. Field of the Invention
This invention relates to an auxiliary artificial heart of an embedded type, embedded in the left or right ventricle of the heart in a human body, and more particularly to an artificial heart operated at high reliability by preventing body fluids such as blood from adversely entering the artificial heart.
2. Description of the Related Art
Conventional artificial hearts are of the diaphragm type, sack type, axially symmetric type, centrifugal type, of pusher plate type or the like. Each of these conventional artificial hearts delivers blood in place of a human heart or by bypassing it.
Recently, an auxiliary artificial heart has been developed which is embedded in a ventricle of a human heart and has the tip end of a nozzle passing through an aorta valve or the like such that blood is delivered from the ventricle into an aorta through the nozzle. The artificial heart does not suppress any function of the human heart when it is installed in the human heart and it delivers additional blood into the aorta when blood pumped out from the human heart is insufficient. The blood is delivered not only by the artificial heart but also by the pulsing or beating of the human heart. Even if the operation of the artificial heart happens to stop, blood is delivered to the body by beating of the human heart.
Naturally, the volume of the part of the artificial heart which is inserted in a ventricle of the human heart must be smaller than the volume of the human heart when it is fully contracted. Such an artificial heart has a pump body comprising a cylindrical axial-flow pump section, a nozzle section provided on its distal end and a driving section provided on the proximal end of the axial-flow pump section. The cardiac apex of a ventricle of a human heart is cut and a short cylindrical cardiac apex ring is embedded therein. The pump section and the nozzle section are inserted in the ventricle through the cardiac apex ring, and the distal end of the nozzle section is inserted in an aorta through its aorta valve or the like. The driving section which has a large volume is embedded in a portion of the thorax which is outside of the human heart.
The artificial hearts has the following problem in connection with the function of a shaft-sealing mechanism provided between the pump section and the driving section. With the artificial heart, a motor and other elements are housed in the driving section, and the rotor of the pump section is driven via a driving shaft extending from the driving section to the pump section. Blood supplied by systemic blood pressure flows through the pump section. In this arrangement, blood is not allowed to enter the space in the driving section. If blood enters the space defined in the driving section, coagulation of blood occurs and the operation of the motor stops.
It is necessary to provide, between the driving section and the pump section, a sealing mechanism for sealing the driving shaft in a liquid tight state in order to prevent blood from entering the interior of the driving section. Since, however, the artificial heart is embedded in a human body, the artificial heart must be operated for a long time without maintenance. It is not easy with the present technology to provide a shaft-sealing mechanism with which perfect sealing is maintained for a long time.